The present invention relates to roller assemblies for use in telescoping slide assemblies having multiple interconnected slide members, the slide assembly extending and retracting along a longitudinal axis of the slide assembly. The invention particularly relates to roller assemblies having a plurality of vertical rollers rotatable about a horizontal axis for movement parallel to the longitudinal axis of the slide assembly, side walls for maintaining the vertical rollers in longitudinal alignment and preventing overlap, and a horizontal roller rotatable about a vertical axis.
Telescoping slide assemblies are used to support loads such as drawers, trays, equipment racks or the like for movement between a retracted position and an extended position. The slide assemblies include interconnected slide members that extend and retract relative to each other along a longitudinal axis of the slide assembly. Typically, a stationary slide member is rigidly attached to a floor or platform, and a load-carrying slide member is attached to the load to be moved. The load-carrying slide member is slidably coupled to an intermediate slide member that is, in turn, slidably coupled to the stationary slide member. Thus, the interconnected slide members cooperate to permit the load to be moved along the longitudinal axis of the slide assembly between a retracted position and an extended position.
Friction between the interconnected slide members can become a major impediment to smooth operation of the slide assembly. It is known to use vertical rollers in the telescoping slide assemblies to reduce friction and thereby increase ease of operation. See, for example, U.S. Pat. No. 3,485,539 to Fall et al., U.S. Pat. No. 3,464,744 to Fall, and U.S. Pat. No. 3,450,466 to Fall et al.
Typically, vertical rollers are oriented to rotate about a horizontal axis and are positioned in channels located between side walls of the interconnected slide members. Vertical rollers alone can improve the ease of operation, but lateral movement of the slide member can reduce the effectiveness of the vertical rollers. Lateral movement of the slide members relative to each other can pinch the vertical rollers on one side of the slide assembly, increasing friction, while allowing room for the vertical rollers on the other side of the assembly to become skewed relative to each other and overlap. When the vertical rollers overlap, they can become wedged, further increasing friction. Of course, when rollers become wedged, the force required to extend or retract the telescoping slide assembly increases dramatically. In extreme cases, the slide assembly locks up and is unable to extend or retract.
In one attempt to minimize lateral movement of the slide members relative to each other to prevent pinching of the vertical rollers, selected vertical rollers were formed to include a central aperture, and a ball bearing was fitted into each aperture. See, for example, U.S. Pat. No. 3,464,744 to Fall. The combination of ball bearings and vertical rollers was successful in eliminating the pinching problem, but was expensive in terms of manufacturing and inventory management costs. Moreover, while the pinching was eliminated, it was still possible for the rollers to become skewed relative to each other and overlap, and the end rollers were still allowed to fall behind.
To eliminate the overlapping problem, it was necessary to maintain the rollers in longitudinal alignment so that each roller moved along the same path, one after another. Applicant experimented with one method which was to remove the ball bearings and place a pair of longitudinally extending side walls alongside the vertical rollers. A rivet connected the side walls through the central aperture of the end rollers. Unfortunately, while the side walls eliminated the overlapping problem, the side walls were subject to being pinched by lateral movement of the slide members.
In order to eliminate the pinching problem while maintaining the side walls to control overlapping, applicant further experimented with bushings incorporated into the mechanism as a replacement for the rivets. The bushings extended laterally beyond the side walls and provided lateral separation to prevent pinching the side walls. Thus, the combination of side walls and bushings solved the pinching and overlapping problems. Moreover, since the ball bearings were no longer needed, the number of parts required was reduced. Unfortunately, the bushings tended to wear excessively and were subject to binding.
Another problem associated with vertical rollers used in telescoping slide assemblies is failure of all of the roller to roll equally due to uneven surfaces on which the rollers move. The surfaces are formed by welding a track to the outer surface of the side walls of the slide members. Those tracks then fit into recesses formed in the side walls of the adjacent slide members. Variations in the surface of the track occur due to unequal heating of the track and slide member during welding. As a result of the uneven track surfaces, the end rollers can lag behind the rest of the rollers as the slide assembly extends or retracts. When the end rollers fall behind, the slide members end up skidding the end roller along, increasing friction, and in severe cases, locking up the slide assembly.
Advantageously, coupling side walls to the end rollers by rivets or bushings solved the problem by keeping all of the rollers together as the slide assembly extended or retracted. However, it was found that the rollers were subject to banging into each other at the end of the assembly travel during extension and retraction, temporarily deforming the rollers and causing flat spots to form on the rollers. In extreme cases, the flat spots were permanently formed on the rollers. When flat spots formed on the rollers, the distance between the end rollers was temporarily reduced. Since the ends of the side walls were coupled to the end rollers, the ends were squeezed toward each other to match the temporarily reduced distance between the end rollers. When the side walls were squeezed, they buckled like an accordian. Buckling of the side walls reduced the clearance between the slide members and the side walls and caused the slide assemblies to lock up.
A roller assembly that provides for longitudinal alignment of the rollers while keeping the rollers moving together and maintaining lateral separation between the slide members would be appreciated by operators of slide assemblies. An assembly that provides those features while eliminating squeezing of the side walls to prevent buckling would be a substantial improvement over conventional assemblies.
The present invention provides a roller assembly for use in a telescoping slide assembly having at least two slide members that are slidably interconnected for movement along the longitudinal axis of the slide assembly. The roller assembly includes first means for maintaining vertical separation between the slide members and second means for maintaining lateral separation between the slide members. The invention also provides third means for longitudinally aligning the first means.
The first means includes a plurality of rollers oriented to rotate about a horizontal axis and the second means includes a bearing oriented to rotate about a vertical axis. The plurality of rollers includes a pair of end rollers, with each end roller having a central aperture.
The third means includes longitudinally extending side walls positioned adjacent the rollers, the side walls having coined segments. The side walls are coupled to the end rollers by a roller insert positioned in the central aperture of the end rollers and a rivet extending through the insert to engage the coined segments.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detained description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.